Prior to the present invention, ink jet printing has been in use in industry for several years. These ink jet printing arrangements have normally utilized a premixed ink ready, as received, for delivery to the printing head. Such premixed ink being communicated by a pump to the print head disposed in such ink jet printing arrangement. As is well known, pumps are generally difficult and costly to maintain due to their numerous moving components.
Applicants are aware of only one ink jet printing arrangement which does not require the use of a pump. This prior art system utilizes a series of elastic members surrounding a container of premixed ink. These elastic members are capable of forcing the ink from the container to the print head disposed in the printing arrangement. However, this system requires over filling of the ink container. The reason such over filling is required is because the force being exerted by the elastic members will obviously decrease as more and more ink is communicated from the container. In addition to the wasted ink, these containers are always thrown away. This, therefore, adds to the printing cost.
Applicants are also aware of European Patent No. 0 266 344 which teaches a fluid jet printing device. This device utilizes a fluid container which supplies a premixed ink to the printing device. Such container is filled with ink and a pressurized gas. The container has an outlet which is adapted to be detachably connected to an inlet port of the printing device. As with other prior art devices, this container is non-refillable and, therefore, costly to use.
Further, such premixed inks normally used in ink jet printing are solvent based and, therefore, present. a number of undesirable problems from an environmental standpoint and oftentimes from a safety standpoint. Obviously the extent of these problems will depend to a large extent on the solvent being used to produce the ink.
Furthermore, because the inks used prior to the present invention were ready for use when shipped, the cost of shipping the ink have generally been high.
Further, adding to the cost of prior art premixed ink used in ink jet printing is that, generally, the shipping containers for the ink are non-returnable. In some cases, disposal of these shipping containers can be a potential problem depending on the solvent used. Applicants are not aware of any equipment commercially available which provides a capability of using an ink concentrate to produce an ink, in situ, that is suitable for use in an ink jet printing head.
It is well known that these ink jet printing arrangements are oftentimes used in high speed, high production assembly lines. As a result, when prior art printing arrangements ran out of ink it was necessary to stop the production line until additional ink supplies could be added. This obviously is costly due to the lost production.